Sarcocystis neurona is an apicomplexan parasite that is the primary etiologic agent of equine protozoal myeloencephalitis in horses. Protective immune responses in horses have not been determined, but interferon-γ (IFN-γ) is considered critical for protection from neurologic disease in mice. The role of adaptive and innate immune responses in control of parasites was explored by infecting BALB/c, IFN-γ knockout (GKO), and severe combined immune deficient (SCID) mice with S. neurona (104 sporocysts/mouse). Immune competent BALB/c mice eliminated parasites within 30 days, with no sign of neurologic disease, whereas GKO mice developed fulminant neurologic disease. In contrast, SCID mice remained healthy throughout the experimental period despite the persistence of parasite at low levels in some mice. Treatment with anti–IFN-γ antibody resulted in neurologic disease in infected SCID mice. Although SCID mice lack adaptive immune responses, they have natural killer (NK) cells capable of producing significant quantities of IFN-γ. Therefore, SCID mice were infected with sporocysts of S. neurona and treated with anti-asialo GM1. Depletion of NK cells, confirmed by flow cytometry, did not result in neurologic disease in SCID mice. These results indicate that IFN-γ mediates protection from neurologic disease in SCID mice. Protective levels of IFN-γ may originate from a low number of nondepleted NK cells or from a non-T cell, non-NK cell population.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.